The novel physics methodology of subquantum kinetics predicted in 1980 that photons should blueshift their frequency at a rate that varies directly with negative gravitational potential, the rate of blueshifting for photons traveling between Earth and Jupiter having been estimated to average approximately (1.3 ± 0.65) × 10−18 s−1, or (1.1 ± 0.6) × 10−18 s−1 for signals traveling a roundtrip distance of 65 AU through the outer solar system. A proposal was made in 1980 to test this blueshifting effect by transponding a maser signal over a 10 AU roundtrip distance between two spacecraft. This blueshift prediction has more recently been corroborated by observations of maser signals transponded to the Pioneer 10 spacecraft. These measurements indicate a frequency shifting of approximately (2.28 ± 0.4) × 10−18 s−1, which lies within 2σ of the subquantum kinetics prediction and cannot be accounted for in terms of known forces acting on the craft. This blueshifting phenomenon implies the existence of a new source of energy that is able to account for the luminosities of red dwarf stars, brown dwarf stars, and planets and their observed sharing of a common mass‐luminosity relation.